Does electron transition from conduction band to valence band takes place only in first Brillouin zone? Or can it happen in any other Brillouin zone?
Why in semiconductor studies, we are only concerned with reduced zone representation of e-k diagram?
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Electron transistion can happen anywhere in the semiconductor structure.
The first Brillouin zone is defined in the reciprocal space. Theoretically, all atoms in the original crystal contribute to the "image" in this reciprocal space. So I believe you may have misunderstood what the Brillouin zone represents.
So everything happening in any Brillouin zone theoretically represents the whole crystal.
So it does not really make sense to say "transition outside the Brillouin zone". The whole crystal is mapped to a cell in the reciprocal space, and a single cell has an effect on all cells in the reciprocal space. So if you look at a single electron in the reciprocal space, then the image of that electron is also there in all Brillouin zones.
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\$\begingroup\$ I am actually saying that transition occurs around k=0 in an ek diagram . \$\endgroup\$ Aug 9 '18 at 8:05
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\$\begingroup\$ Can electron jump from say k=2pi/a to k=0?? \$\endgroup\$ Aug 9 '18 at 8:07
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\$\begingroup\$ The Brillouin zone is the whole cell, not just around k=0. But yes, electron transition can happen anywhere. I'll edit my post to include more information. \$\endgroup\$– Sven BAug 9 '18 at 8:07
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\$\begingroup\$ I edited my post. I believe I only understood your question after you second comment. \$\endgroup\$– Sven BAug 9 '18 at 8:19